Cretin

Shake, jerk, and yelp for joy
Self gratification a favorite toy
Clapping hands, nervous twitch
Autistic stimming a neural glitch
Body spasms at the brain's own leisure
Needing constant stimulus for pleasure
Uncontrolled spazzing lots of fun
Never bored, we jerk and run
Stick out my tongue, absently drool
Shambling fast, going to touch you
My social skills put to the test
Public behavior a total mess